NEW YORK -- The search is on for the shooter who killed a food delivery worker on the job in Queens.
The 45-year-old father of three was.
Sources say police are looking at a disgruntled customer as a possible person of interest.
Outside the Great Wall on Queens Boulevard, flowers and condolence messages cover the front gate of the still shuttered restaurant, CBS2's Christina Fan reported Monday.
"Miss you my friend," some said, in reference to the warmness Zhiwen Yan greeted customers with for more than a decade.
"He was the delivery man, everybody knew him. Always a smile, never aggression," said Andre Tsybulink.
"Always on his scooter, he'd wave to everybody and say, 'Hello my friend, hello my friend,'" Alicia Murray said.
"I can't breathe when I hear that," one woman told CBS2's Kevin Rincon. "I miss him so much."
She said Yan would help her cross the street with her food.
"He was just a pure gentleman, a pure human being. It's so sad. A young man ... for no reason," added Nina Barbara of Forest Hills.
Surveillance video from Saturday night shows Yan, 45, getting on his scooter and pulling onto 108th Street when someone walked up and shot him in the chest.
According to sources, police are looking to question a 50-year-old disgruntled customer who restaurant owner Kai Yang said has been seeking retribution since last November because he didn't get enough duck sauce with an order, first vandalizing Yan's car, then menacing him with a gun.
"He paid for the food," Yang said. "Twenty minutes later, he came back, tried to ask for a refund. We told him we can't take back the food because of COVID, and he started using racist language."
Yang said he gave a description of the customer's Lexus to police. Sources said it matched a vehicle seen fleeing the murder scene.
"He was like family to me. I feel terrible, just terrible," Yang said of Yan, who leaves behind a grieving wife and three children, the youngest just 2 years old.
Neighbors said Yan was hustling, on the move, working 11 a.m. to 10 p.m. every day at the restaurant, trying to provide his children with a better life.
"He's the kind of guy that works so hard. He was in all types of weather, never had a bad word to say, always smiling when he would come up," one woman said.
While the community continues raising money for Yan's family, Yang hopes police are making fast progress.
He said the employees are too afraid and devastated to return until an arrest is made.
Yan and his wife also opened a laundromat together to support their family.
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